IP Multimedia services provide a dynamic combination of voice, video, messaging, data, etc. within the same session. By increasing the number of basic applications and the media that it is possible to combine, it is possible to increase the number of services offered to the end users, and thus to enrich the inter-personal communication experience. This will lead to a new generation of personalized, rich multimedia communication services, including so-called “combinational IP Multimedia” services that are considered in more detail below.
IP Multimedia Subsystem (IMS) is the technology defined by the Third Generation Partnership Project (3GPP) to provide IP Multimedia services over mobile communication networks (3GPP TS 22.228, TS 23.218, TS 23.228, TS 24.228, TS 24.229, TS 29.228, TS 29.229, TS 29.328 and TS 29.329 Releases 5 to 7). IMS provides key features to enrich the end-user person-to-person communication experience through the use of standardised IMS Service Enablers, which facilitate new rich person-to-person (client-to-client) communication services as well as person-to-content (client-to-server) services over IP-based networks. The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between user terminals (or user terminals and application servers). The Session Description Protocol (SDP), carried by SIP signalling is used to describe and negotiate the media components of the session. Whilst SIP was created as a user-to-user protocol, IMS allows operators and service providers to control user access to services and to charge users accordingly.
The boundaries between the services provided by telecommunication operators, TV operators, and internet service providers are disappearing, and such companies are all offering customers all three services (so called “triple play”). For telecommunication operators wishing to offer TV services, a popular choice is to utilize so called IPTV which delivers the TV service over IP and the customer's broadband connection (e.g. ADSL, VDSL, Public Ethernet, etc.).
IPTV has a limited bandwidth at its disposal in the “first mile” of the broadband access from the xDSL modem and the broadband access (DSLAM). Linear content delivery, in which all channels in a subscription (“program package”) are simultaneously delivered to the set top box (STB), is not suitable for IPTV due to the limited bandwidth. xDSL connection capacity varies depending on the DSL version used and the distance of the “first mile”. ADSL can provide a capacity between 3 to 8 Mbps, whereas ADSL2 promises to deliver up to 25 Mbps downstream and VSDL data rates greater than 30 Mbps. Standard quality MPEG2 content requires 2 Mbps per channel, and HDTV will require 8-10 Mbps per channel. Luckily, the new MPEG4 standard will decrease the required bandwidth to half with the same quality as the MPEG2 coded content. Nevertheless, the available bandwidth is a scarce resource, and IPTV solutions must limit the number of channels to be delivered over the “first mile”.
Existing time-shift/chase-play solutions are either based on proprietary network technology or on PVRs in the home. The solution described herein, utilizes the standardized IMS communication system and its network architecture, and a PVR residing in the Network to limit the traffic transmitted over the first mile connection to a home.
With the convergence between IPTV services and the IMS infrastructure a new plethora of possibilities opens up for the end user to utilize the TV set. Videoconferencing, interactive gaming, personalized advertisement or interactive TV programs with viewers' feedback become a reality that is easily achievable using IMS. However, many of these applications require extensive communication between the STB and the different application servers, so that, every time a new service requires to be added to the user experience (for example when the user receives a videoconferencing call while watching TV) using a conventional IPTV system, there is a setup delay associated with setting up the different control channels and receiving the required information.